A solar selective coating is a coating or series of coatings applied to a substrate that will absorb ninety (90) percent plus of the solar radiation and emit less than thirty (30) percent of the infra-red radiation in the range of 0.3 to 1.9 microns. In contrast non-solar selective coatings absorb and emit 90 to 95 percent of the solar radiation.
Although much work has been done in the area of solar selective coating development, the processes of application have involved bringing of the solar array (collector) surfaces into the application procedures. For example, where the coating is painted, the solar arrays had to be painted and baked. Where the coatings were vacuum plated, electro or electroless plated or chemically converted, the solar array had to be subject to a number of cleaning, pretreatment and finish cycles in chambers or paths. The number of process cycles will vary with the type of substrate and solar selective coating that was applied, but in each instance the solar collecting surfaces are intrinsic to the application processing.
Various approaches to solar selective coatings, solar energy collectors, light reflective films are discussed in the prior art. See, for example, the following U.S. Pat. Nos., Palmquist et al., 2,543,800; Tabor, 2,917,817 and 3,129,703; Langley, 3,176,678 and 3,176,679; Garling, 3,253,971; Doctoroff et al., 3,645,600; Boebel et al., 3,810,777; Lowery, 3,920,413; and Vesely, 3,936,567; also, N.A.S.A. Tech. Brief LEW-12614 (April 1976). Plating processes of interest to the process of the present invention are shown in Davis, U.S. Pat. No. 1,124,114 and Grupe U.S. Pat. No. 1,731,415.